The field of the invention relates generally to high temperature high frequency magnet wire, and more particularly to a composite magnet wire coated with a coating that includes alumina nano particles dispersed in a polyimide polymer.
Coated electrical conductors typically include one or more electrical insulation layers, also referred to as wire enamel compositions, formed around a conductive core. Magnet wire is one form of coated electrical conductor in which the conductive core is a copper wire or copper alloy, and the insulation layer or layers include dielectric materials, such as polymeric resins, coated peripherally around the conductor. Magnet wire is used in the electromagnet windings of transformers, electric motors, and the like. Because of its use in such windings, the insulation system of magnet wire must be sufficiently flexible such that the insulation does not delaminate or crack or otherwise suffer damage during winding operations. The insulation system must also be sufficiently abrasion resistant so that the outer surface of the system can survive the friction, scraping and abrading forces that can be encountered during winding operations. The insulation system also must be sufficiently durable and resistive to degradation so that dielectric properties are maintained over a long period of time.
In addition, magnet wire also is used in the construction of transformers, inductors, motors, headphones, loudspeakers, hard drive head positioners, potentiometers, and electromagnets, among other applications. Magnet wire is the primary insulation used in electric machines, motors, generators and transformers as winding insulation. The magnet wire carries alternating current and generates a magnetic field and induced electric power. Magnet wire typically uses multiple layers of polymer insulation to provide a tough, continuous insulating layer. Magnet wire insulating coatings may be, in order of increasing temperature range, polyurethane, polyamide, polyester, polyester-polyimide, polyamide-polyimide, and polyimide. Polyimide insulated magnet wire is capable of operation at up to 250° C.